As a film based on a transparent substrate for shading light, Japanese Laid-open Patent Publication No.6-222354 discloses a shading film as shown in FIG. 16. The shading film on a substrate 163 includes a chromium oxide film 162 which is substantially transparent in a visible region and a chromium film 161 which is substantially opaque in a visible region. The chromium oxide film 162 has a thickness between 50 nm and 75 nm to make reflected light from the layers (the chromium oxide film 162 and the chromium film 161) interfere so that the shading film shows both low transmittance and low reflectance.
While the shading film as described above succeeds in lowering light reflectrance to some extent, the light reflectance is reported to still remain at about 6.5% in Japanese Laid-open Patent Publication No.6-222354. Such a level of a light reflectance is not sufficient for applying a shading film to an optical device for an optical equipment such as a light pickup device for an optical-disk equipment, a dividing-color prism for a video-movie camera, an imaging sensor and various kinds of lens.